Add Grafana dashboard and wp-prometheus integration (v0.7.5)

- Add example Grafana dashboard with 24 panels for license metrics
- Register dashboard with wp-prometheus via hook
- Add dashboard documentation with PromQL examples and alerting rules
- Update README with monitoring section

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Metrics/PrometheusController.php

@@ -43,6 +43,29 @@ final class PrometheusController
         }
 
         add_action('wp_prometheus_collect_metrics', [$this, 'collectMetrics']);
+        add_action('wp_prometheus_register_dashboards', [$this, 'registerDashboard']);
+    }
+
+    /**
+     * Register Grafana dashboard with wp-prometheus
+     *
+     * @param object $provider The dashboard provider object
+     */
+    public function registerDashboard(object $provider): void
+    {
+        $dashboardFile = WC_LICENSED_PRODUCT_PLUGIN_DIR . 'docs/grafana-dashboard.json';
+
+        if (!file_exists($dashboardFile)) {
+            return;
+        }
+
+        $provider->register_dashboard('wc-licensed-product', [
+            'title'       => __('WC Licensed Product - License Metrics', 'wc-licensed-product'),
+            'description' => __('Monitor license status, downloads, API usage, and validation errors.', 'wc-licensed-product'),
+            'icon'        => 'dashicons-admin-network',
+            'file'        => $dashboardFile,
+            'plugin'      => 'WC Licensed Product',
+        ]);
     }
 
     /**